<!--
Copyright 2012 Google Inc. All Rights Reserved.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
-->

<!DOCTYPE html>
<style>
canvas {
  border: silver solid 1px;
  padding: 5px;
}
span {
  display: inline-block;
  padding: 5px;
}
</style>
<body>

<script src="../../web-animations.js"></script>
<script>
"use strict";

var size = 100;
var duration = 3.0;

function testStep(numSteps, position) {
  var canvas = document.createElement('canvas');
  canvas.width = canvas.height = size;
  var ctx = canvas.getContext('2d');
  ctx.beginPath();
  var span = document.createElement('span');
  span.appendChild(canvas);
  span.appendChild(document.createElement('br'));
  span.appendChild(document.createTextNode('steps: ' + numSteps));
  span.appendChild(document.createElement('br'));
  span.appendChild(document.createTextNode('position: ' + position));
  document.body.appendChild(span);
  return new Animation(ctx, {
    sample: function(timeFraction, iteration, target) {
      var inputTimeFraction = player.currentTime / duration;
      if (target.lastTimeFraction !== timeFraction) {
        target.beginPath();
        target.moveTo(inputTimeFraction * size,
            size - target.lastTimeFraction * size);
        target.lineTo(inputTimeFraction * size, size - timeFraction * size);
        target.strokeStyle = 'silver';
        target.stroke();
        target.beginPath();
        target.strokeStyle = 'blue';
      } else {
        target.lineTo(inputTimeFraction * size, size - timeFraction * size);
      }
      target.lastTimeFraction = timeFraction;
      target.stroke();
    },
  }, {
    iterationDuration: duration,
    timingFunction: 'steps(' + numSteps + ', ' + position + ')',
  });
}

// TODO: Making player global like this is is rather ugly. It would be nice if
// the animation or player were passed to the custom animation effect's sample
// function.
var player = document.timeline.play(new ParGroup([
  testStep(1, 'start'),
  testStep(1, 'middle'),
  testStep(1, 'end'),
  testStep(3, 'start'),
  testStep(3, 'middle'),
  testStep(3, 'end'),
  testStep(10, 'start'),
  testStep(10, 'middle'),
  testStep(10, 'end'),
]));

</script>
